Any ideas?
Can we do an efficient mix of swordsman and alchemist? Or swordmsman/magic? I don't think mixing the 3 is viable, is it? What about pure class? Any of the 3 stands out when Insane diff punishment comes to mind?

I thought Swordsman was mostly useless on Hard.

I would never bother with Impossible mode, but if I was going to do it, I probably wouldn't bother with swordsman at all, as the only skill I found at all useful in that entire tree was the one half-way down it that let you hit multiple enemies, and I'm guessing you don't want to even let yourself get into a situation where you need to hit multiple enemies on insane.

I'd probably beeline for anything that helped out potions/traps/bombs, and the utility signs (not Igni). Throwing daggers might be useful. Never used them much since I found it a pain to keep them stocked, but pain shouldn't be an issue if you're trying Insane. :p